1. Technical Field
The invention relates to an electromechanical device, and a movable body and a robot each using the electromechanical device.
2. Related Art
As an example of a rotary electric appliance (also referred to as an “electromechanical device” in the present specification) such as an electric motor or an electric generator, there can be cited an inner-rotor coreless electromechanical device provided with a rotor having permanent magnet disposed to have a roughly cylindrical shape as a rotor magnet, and a stator having an air-cored (coreless) magnetic coil disposed to have a roughly cylindrical shape in the outer periphery of the rotor. As a casing of the electromechanical device, there has been used in the past a metal easy to provide sufficient lightweight property, strength property, heat-resistance property, and so on such as an aluminum alloy.
Here, although the magnetic flux from the rotor magnet is basically arranged to close as a magnetic circuit on the inner side of a coil back yoke disposed in the outer periphery of the magnetic coil, in reality, leakage of the magnetic flux occurs on the outer peripheral side of the coil back yoke due to the arrangement for downsizing. Therefore, eddy current is caused in the casing covering the stator in the outer periphery of the coil back yoke, and the loss due to the eddy current thus caused, namely the so-called eddy-current loss, hinders an improvement inefficiency of the electromechanical device.
JP-A-10-210690 and JP-A-2002-322978 are examples of a related art document.